Regarding the relationship between RSTP and STP, which of the following is correct statement?

Regarding the relationship between RSTP and STP, which of the following is correct statement?
A . RSTP is defined in the old EE802.1 D standard. Its protocol concept is the same as STP, but it has improved the convergence time.
B . Switches running RSTP can work together with switches running STP and improve the convergence time of STP.
C . RSTP can realize load sharing of data from different VLANs on Trunk links based on STP.
D . RSTP has all the functions of STP, but it only uses one type of BPDU

Answer: D